Lined engine members and methods of making the same or the like



March 26, 1963 J. B. THOMAS 3,032,752

LINED ENG MEMBER ND METHODS OF MAKING E SAME LIKE Filed April 1961 INVENTOR- JESSE B. THOMAS W2. HIS ATTORN s United States Patent 3,082,752 LINED ENGENE MEMBERS AND METHODS OF MAKENG THE SAME OR THE LIKE Jesse B. Thomas, Henrico (Iounty, Va., assignor to Reynolds Metals Company, Richmond, Va, a corporation of Delaware Filed Apr. 4, 1961, Ser. No. 1%,615 8 Claims. ((11. 123-32) This invention relates to improved cylinder heads and pistons for compression ignition engines such as diesel engines or the like and to improved methods for making the same or the like.

It is well known that diesel engines ignite the fuel injected into the cylinders thereof solely by the temperature of the compressed air therein, the air being compressed between the pistons and the cylinder head of the engine to such an extent that the compressed air is heated to around 1000* F; and is adapted to ignite the fuel subsequently injected into the compression chambers defined between the pistons and the cylinder head.

When such engines are made from heat conducting materials, such as aluminum-containing metallic material and the like, a higher compression ratio for the engine is required to cause spontaneous ignition because the pistons and cylinder head of such engines readily conduct the heat away from the compressed air in the compression chambers defined thereby. Therefore, in order to provide compressed air at a temperature sufficient to ignite the fuel, the compression ratio must be greater for an aluminum engine than the compression ratio for an engine formed from metallic materials having a lower heat conductivity than aluminum. Further, even if the compression ratio of such an aluminum engine is increased it has been found that such engines are relatively hard to start in cold weather because the tendency to conduct the heat away from the compressed air is greatly enhanced.

However, it is more desirable to form the various parts of an engine from aluminum-containing metallic material because the same is lightweight, non-corrosive, inexpensive and particularly adaptable for being air-cooled. But, the greater the compression ratio for an engine the greater the tendency for the parts to wear and become damaged.

Therefore, in the past, various diesel engine manufacturers and the like have attempted to protect the compression chamber-defining surfaces of the cylinder heads and pistons with heat insulating materials that tend to prevent the heat of the compressed air from being conducted away by the pistons and cylinder heads whereby lower compression ratios can be utilized than the compression ratios required for the same engines without such insulating materials. Further, such insulating materials increase the thermal efiiciency of the engine because less heat is transferred through the Walls of the combustion chamber.

However, such prior known heat-insulating means and methods are relatively expensive because the same are difficult to install and require many production steps to produce. Further, such prior known heat-insulating ma terials are also expensive. Such expense is greatly noticeable when the cylinder head and pistons are formed of aluminum-containing metallic material because of the difficulty in properly securing the heat-insulating material to the desired surface thereof.

According to the teachings of this invention, however, improved internal combustion engines and improved methods of making the same or the like are provided whereby improved heat-insulating means are disposed on the combustion chamber-defining surfaces of the cylinder heads and pistons in an inexpensive and non-time consuming manner to prevent heat transfer from the air compressed thereby to the engine block whereby relatively low compression ratios can be utilized even though the cylinder head and/or pistons are formed of aluminumcontaining metallic material.

In particular, one method of this invention is to precover the combustion chamber-defining surface of the cylinder head or piston or both of an engine with a layer of heat-insulating material selected from the group of either a heat-insulating ceramic material or carbon.

If carbon is selected, the carbon layer can be provided by simply burning carbon-forming material, such as acetylene or the like, in the region of the desired surface to deposit a layer of carbon thereon of the desired thickness, the layer of carbon providing a heat-insulating barrier between the compression chamber and the engine member carrying the same. The layer of carbon is applied before the engine is assembled. Therefore, even if the pistons and cylinder head are formed of aluminumcontaining metallic material, the heat-insulating layer of carbon on the surfaces thereof reduce the transfer of heat of the air compressed thereby to the remainder of the engine whereby such aluminum engine will even readily start in extremely cold weather.

If the ceramic material is selected, the ceramic material can be readily applied to the desired surfaces of the pistons and cylinder head of an engine to provide a heat-insulating barrier between the compression chamher and the remainder of the engine in the same manner as the carbon layer described above.

Accordingly, it is an object of this invention to provide an improved internal combustion engine or the like having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved engine member having a surface for defining part of a compression chamber thereof.

Another object of this invention is to provide an improved method for making such an engine member or the like.

Other objects, uses, and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIGURE 1 is a cross-sectional view of an internal combustion engine incorporating various features of this invention.

FIGURE 2 is an enlarged, fragmentary, cross-sectional view of the piston illustrated in FIGURE 1 and illustrates a carbon layer applied to the compression chamber-defining surface thereof by the method of this invention or the like.

FIGURE 3 is a View similar to FIGURE 2 and illustrates another embodiment of this invention.

FIGURE 4 is a perspective view illustrating one method of this invention for forming the piston structure illus trated in FIGURE 2.

FIGURE 5 is a schematic, flow diagram illustrating the method of this invention for forming the piston structure illustrated in FIGURE 3.

While the various features of this invention are hereinafter described as being particularly applicable for cylinder heads and pistons of diesel engines or the like, it is to be understood that the various features of this invention are also applicable to other types of internal combustion engines or the like. Further, while the various fea tures of this invention are particularly concerned with engine members formed of aluminum-containing metallic materials, the same can be readily utilized with engine members formed of any metallic materials, if desired. Therefore, this invention is not to be limited to only the application thereof illustrated in the drawings, as the drawings are merely to illustrate one of the many uses of this invention.

Referring now to FIGURE 1, an improved diesel engine of this invention is schematically illustrated and is generally indicated by the reference numeral 10. While the details and operation of the engine do not form any part of this invention, sufiicient structure and mode of operation thereof will be described to better understand the importance of this invention in providing a heat-insulating barrier between the compression chambers of the engine and the remaining structure thereof to greatly enhance the operation of the engine in a manner hereinafter described.

The engine 10 includes a cylinder-defining member 11 carried by a cylinder block construction 12 and having the upper end thereof closed by a cylinder head 13 secured to the cylinder block 12 in any suitable manner. The cylinder head 13 carries an air inlet valve 14, an exhaust valve 15, and a fuel injecting means 16, the valves 14 and 15 and fuel injecting means 16 being operated in a desired sequence by conventional means in a manner well known in the art.

A cylindrical piston 17 is disposed in the cylinderdefining means 11 and is interconnected to a crankshaft 18 by a conventional connecting rod 19 in a manner well known in the art.

While only one such cylinder-defining member 11 is illustrated for the engine 10, it is to be understood that the engine 10 can have one or more such cylinderdefining members 11 as desired.

The lower surface 13a of the cylinder head 13 and the upper surface 17a of the piston 17 cooperate with the cylinder-defining member 11 to form a compression chamber 20 therebetween, the chamber 20 also acting as a combustion chamber in a manner hereinafter described.

When the piston 17 initially moves downwardly away from the cylinder head 13, the air inlet valve 14 opens permitting air to be drawn into the chamber 20. After the piston 17 has reached the bottom of its stroke and begins to travel upwardly toward the cylinder head 13, the valve 14 closes thereby permitting the air in the chamber 20 to be compressed between the surfaces 13a and 17a of the cylinder head 13 and piston 17 as the piston 17 travels upwardly toward the cylinder head 13. As the piston 17 nears the top of its upward compression stroke, the air compressed in the chamber 20 heats up to around 1000 Fahrenheit. When the compressed air has reached such temperature and the piston 17 has reached the top of its compression stroke, the fuel injecting means 16 injects a predetermined amount of fuel into the chamber 20 whereby the heat of the compressed air trapped therein ignites the fuel in the chamber 213. The subsequently expanding combustion gases in the chamber 20 drives the piston 17 downwardly in its power stroke to rotate the crankshaft 18. Thereafter, when the piston 17 subsequently rises in the cylinder-defining member 11, the valve 15 opens and permits the burnt gases to be expelled from the chamber 20 to the atmosphere in a manner well known in the art.

The sequence of operation of the engine 10 is then repeated to perform another power stroke of the piston 17.

As previously stated, when the cylinder head 13 and piston 17 are formed of a good heat-conducting material, such as aluminum-containing metallic material or the like, the heat of the air compressed within the chamber 20 tends to be conducted away from the chamber 2%) by the cylinder head 13 and piston 17 to other parts of the engine whereby the temperature of the compressed air in the chamber 20 is lowered below the desired i nfition temperature of the fuel subsequently injected therein when the compression ratio of the engine 10 is the same as the compression ratio of a similar engine formed of materials having a lower heat conductivity than aluminum.

Therefore, the surfaces 13a and 17a of the cylinder head 13 and piston 17 of this invention are pre-covered with a layer of insulating material 21 of this invention to provide a heat insulating barrier between the compression chamber 20 and the cylinder head 13 and piston 17 to prevent such heat transfer from the air compressed in the chamber 29. In this manner, the engine 10 having the heat-insulating material 21 of this invention can have a lower compression ratio than the compression ratio of a similar engine without the heat-insulating material 21 regardless of whether the engines are formed of aluminum-containing metallic material or any other metallic material.

If desired, the lower surfaces 14a and 15a of the valves 14 and 15 can be likewise covered with the insulating material 21, if desired.

In the past, various manufacturers and the like have attempted to cover the surfaces 13a and 17a of the cylinder head 13 and piston 17 with a metallic material having a lower heat conductivity than the base material of the cylinder head 13 and piston 17. However, such bonding methods are relatively expensive and time-consuming. Further, when the cylinder head 13 and/or piston 17 are formed from aluminum-containing metallic material, the problem of bonding such metallic insulating material is greatly aggravated because of the inherent problem of bonding a dissimilar metallic material to an aluminum-containing metallic material.

However, according to the teachings of this invention, either a layer of carbon or a layer of heat-insulating ceramic material is bonded to the surfaces 13a and 17a of the cylinder head 13 and piston 17 by the methods of this invention in a simple and effective manner to prevent the heat transfer from the compressed air during the compression cycle of the engine as well as heat transfer from the combustion gases during the combustion cycle of the engine.

In particular, as illustrated in FIGURE 2, the surface 17a of the piston 17 is covered with a layer of carbon 22 in a suitable manner whereby the layer of carbon 22 provides a heat-insulating barrier between the piston 17 and the compression chamber 20 defined in part thereby. While the cylinder head 13 is not illustrated in the same manner as the piston 17 in FIGURE 2, it is to be understood that the heat-insulating material 21 thereof can also be formed from a layer 22 of carbon.

While the layer 22 of carbon can be deposited on the cylinder head 13 and piston 17 in any desired manner, one inexpensive and simple method is illustrated in FIGURE 4 wherein carbon-forming material is burned in the region of the surface 17a thereof to form the carbon layer 22 in such a manner that the carbon layer 22 is not subsequently burned off of the piston 17 during use thereof but actually promotes the depositing of carbon thereon during subsequent burning of the fuel in the engine 11 to replace any of the carbon layer 22 burned off during operation of the engine 10.

In particular, the carbon layer 22 can be provided by simply burning acetylene in the region of the surface 17a of the piston 17. This can be accomplished by a conventional oxygen-acetylene torch 23 being supplied with oxygen from a container 24 and acetylene from a container 25 with the flame 26 of the torch 23 being played across the surface 17a of the piston 17 to deposit the carbon layer 22 thereon. It has been found that a carbon layer 22 between and of an inch can be applied by this method and performs a satisfactory heatinsulating function.

The layer of carbon 22 can also be applied to the surface 13a of the cylinder head 13 and to the lower surfaces of the valves 14 and 15 in the same manner as the layer 22 of carbon is applied to the piston 17 in FIGURE 4.

While the method illustrated in FIGURE 4 discloses utilizing acetylene as the carbon-forming material, it is to be understood that any other suitable carbon-forming material can be burned in the region of the surface 17a of the piston 17 to form the carbon layer 22.

Alternately, a preformed layer of compressed carbon can be secured to the surfaces 13a and 17a of the cylinder head 13 and piston 17 by a suitable heat resistant adhesive or the like to provide the heat-insulating barrier 21 between the compression chamber 20 and the chamber-defining surfaces 13a and 17a of the cylinder head 13 and piston 17 in the same manner as the carbon layer 22 previously described.

Another embodiment of this invention is illustrated in FIGURE 3 whereby a ceramic layer 27 is disposed on the surface 17a of the piston 17. Similarly, a ceramic layer 27 can be disposed on the surface 13a of the cylinder head 13, although the same is not illustrated.

One method for depositing such a ceramic layer 27 on the surface 17a of the piston 17 is illustrated schematically in FIGURE 5 wherein a piston 17 is formed at station 28 in any suitable manner and is then transported to station 29 where a layer of ceramic material 30 is sprayed on the surface 17a of the piston 17 by conventional spray apparatus 31 or the like to the desired thickness. Thereafter, the coated piston 17 is transported to a heating device 32 at station 33 where the ceramic material 30 is baked and bonded to the piston 17. After the ceramic material 30 has been bonded to the surface 17a of the piston 17, the completed piston 17 is removed from the heating device 32 to be subsequently used in the engine 10.

It is to be understood that the ceramic material 30 can also be applied to the surface 13:: of the cylinder head 13 in substantially the same manner as it is applied to the piston 17.

While the ceramic material 30 is illustrated as being sprayed onto the surface 17a of the piston 17, it is to be understood that a preformed piece of ceramic material can be provided in any suitable manner and be, thereafter, suitably bonded to the piston 17 by a suitable heat resistant adhesive or the like.

Therefore, it can be seen that whether the piston 17 and cylinder head 13 are provided with a carbon layer 22 or a ceramic layer 27, the engine will function in the same manner whereby the layer 21 of heat-insulating material of this invention will tend to prevent the heat of the air compressed in the chamber thereof from being conducted away from the chamber 20' by the cylinder head 13 and piston 17 and thereby lower the temperature of the compressed air below the ignition point of the fuel subsequently entering the chamber 20. The layer 21 of the heat-insulating material of this invention will also increase the thermal efiiciency of the engine by preventing heat transfer from the combustion gases of the engine to other parts of the engine.

It is also to be understood that the piston 17 could be covered with a layer of ceramic material 27 or carbon 22 and the cylinder head 13 can be covered with the other heat-insulatnig material of this invention, if desired. It will be apparent that the heat-insulating materials may be applied to the pro-combustion chambers as well as to the tops of the valves and pistons in the combustion chambers to facilitate easy starting.

While the engine 10 previously described is a diesel engine, it is to be understood that the heat-insulating materials of this invention can also be utilized with compression ignition engines generally but not to Otto cycle engines. It would be disadvantageous to use the teachings of this invention in Otto cycle engines, whereas when employed in compression ignition engines it is possible to increase the thermal efiiciency thereof as well as the starting capabilities of the engines.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be used, all coming Within the scope of the claims which follow.

- What is claimed is:

1. In a diesel engine, a cylinder head of aluminumcontaining metallic material and having a surface for defining part of a compression chamber, and a piston of aluminum-containing metallic material and having a surface for defining another part of said compression chamber, each of said surfaces of said cylinder head and said piston having at least the major portions thereof pro-covered with a layer of heat-insulating substantially pure and uncombined natural carbon before said engine is operated.

2. In a diesel engine, a cylinder head of aluminumcontaining metallic material and having a surface for defining part of a compression chamber, said surface of said cylinder head having at least the major portion thereof pro-covered with a layer of heat-insulating substantially pure and uncombined natural carbon before said engine is operated.

3. In a diesel engine, a piston of aluminum containing metallic material and having a surface for defining part of a compression chamber, said surface of said piston having at least the major portion thereof precovered with a layer of heat-insulating substantially pure and uncombined natural carbon before said engine is operated.

4. A method comprising the steps of providing an aluminum-containing metallic member having a surface for defining part of a compression chamber for a diesel engine, and pre-covering at least the major portion of said surface of said member with a heat-insulatnig layer of substantially pure and uncombined natural carbon before said engine is operated.

5. A method for pro-insulating a surface of an aluminum-containing metallic member which is adapted to define part of a compression chamber of a diesel engine before said engine is operated comprising the step of burning carbon-forming material in the region of said surface to provide a layer of heat-insulating substantially pure and uncombined natural carbon on at least the major portion of said surface.

6. A method as set forth in claim 5 wherein said carhon-forming material is acetylene.

7. A method for pre-insulating the surface of a cylinder head which is adapted to define part of a compression chamber of an engine before said engine is operated comprising the step of burning carbon-forming material in the region of said surface to provide a layer of heat-insulating substantially pure and uncombined natural carbon on at least the major portion of said surface.

8. A method for pro-insulating the surface of a piston which is adapted to define part of a compression chamber of an engine before said engine is operated comprising the step of burning carbon-forming material in the region of said surface to provide a layer of heat-insulating substantially pure and uncombined natural carbon on at least the major portion of said surface.

References Cited in the file of this patent UNITED STATES PATENTS 993,135 Wolfe May 23, 1911 1,320,064 Junkers Oct. 28, 1919 1,398,775 Gerleman Nov. 29, 1921 2,075,388 De Cloud Mar. 30, 1937 2,239,414 Eddison Apr. 22, 1941 2,657,961 Von Lassberg Nov. 3, 1953 2,833,264 Dailey et al. May 6, 1958 2,978,360 Bradstreet et al Apr. 4, 1961 FOREIGN PATENTS 786,110 Great Britain Nov. 13, 1957 

1. IN A DIESEL ENGINE, A CYLINDER HEAD OF ALUMINUMCONTAINING METALLIC MATERIAL HAVING A SURFACE FOR DEFINING PART OF A COMPRESSION CHAMBER, AND A PISTON OF ALUMINUM-CONCATINING METALLIC MATERIAL AND HAVING A SURFACE FOR DEFINING ANOTHER PART OF SAID COMPRESSION CHAMBER, 